And some say the shortage is a very serious situation.
In a notice to health care providers, the Food and Drug Administration blamed the supply problems on a spike in demand due to the severity of influenza.
Even outpatients with the flu are often given I-V fluids at a hospital because they can be dehydrated from high fever.
However, hospital pharmacists says there's never been a shortage of I-V fluids during a previous flu season, including the 2009-2010 H1N1 'swine flu' outbreak.
The shortage began in the fall, and some health officials think production problems are at least partially to blame.
Baxter International, one of the largest makers of I-V saline, shut down a plant for 2 weeks over the holidays for FDA inspections and upgrading equipment. At the time it notified customers of the shutdown, it said there was sufficient supply to fulfil customer orders.
It also notified customers it would temporarily stop making the 150 mL bags, because of a higher demand for the 250 mL ones. It plans to resume production between April and June.
The shortage is in sodium chloride 0.9% injection bags.
Saline solution isn't stockpiled in big quantities in the supply chain or most hospitals, because it is used so much. Millions of bags are used during a routine week.
When one company experiences a supply problem, it often triggers similar shortages for other suppliers as hospitals try to find alternative sources.